Modeling of the vibro-acoustic behavior of an air-core coil

Due to the changing environmental standards and constraints, noise reduction solutions generated by high voltage devices are needed. Among these devices, transformers and reactors are generally the ones producing the highest level of permanent noise. A high-voltage device generates electromagnetic fields that interact with the electric current and induce vibration of the structural elements of the device and become a source of noise. This work aims at understanding and modeling the vibro-acoustic behavior of dry type air-core reactors in order to reduce the electromagnetic noise they generate. The objective of this paper is to present the numerical model chain of the dry type reactors from its electrical feed that induces electromagnetic excitations corresponding to Lorentz forces, to its vibro-acoustic response. To do this, we carried out the study of a single coil prototype used for the manufacture of loudspeakers. First the electromagnetic model, performed with FLUX (Altair), gives the distribution and the amplitudes of the Lorentz forces applied on the mechanical structure of the coil. The mechanical model, performed with NASTRAN, allows us to determine the normal modes of the coil. Both outputs will then be used to calculate the vibro-acoustic response in the VaOne software (ESI Group). The sound pressure level calculated by the multiphysics simulation will be presented and compared to experimental results measured in several points around the coil.